1. Field of the Invention
The invention relates to an apparatus for flattening a floor over which a fresh concrete or mortar has been just placed in a construction site for constructing a concrete floor in a building.
2. Description of the Related Art
A conventional process for constructing a concrete floor in a building generally includes steps of levelling a fresh concrete having been placed on a floor in a construction site, leaving the concrete a few hours to allow the concrete to be cured, uniformly pressurize and flatten the floor by means of an apparatus called a trowel, and manually finishing the concrete by those skilled in the art through the use of a planarizer. The trowel is of a type on which an operator rides.
However, it is difficult to completely flatten a concrete surface in the step of levelling the concrete, roughness (concave and convex portions in the range of ±about 5 to 8 millimeters) usually remains without being removed at a concrete surface before the concrete surface is flattened by means of a trowel. Since it is not possible to remove such roughness out of a concrete surface even by levelling the concrete floor by means of a trowel and/or finishing the concrete floor through the use of a planarizer, the roughness remains at a finished floor, resulting in degradation of floor quality.
As an apparatus used for curing a ground in a road construction site, there is well known a hand-guided type oscillation roller (for instance, see Japanese Patent Application Publication No. 2005-307475).
Furthermore, as an apparatus used for levelling a surface of interlocking blocks to be laid on a footway, there is known a finisher commercially available from Mikasa Industry Inc. in the tradename “Block Plate”, for instance. FIG. 6 is a perspective view of the finisher “Block Plate”.
As illustrated in FIG. 6, the finisher 60 includes a plurality of rollers 61 each having an outer surface composed of hard rubber, a main frame 62 rotatably supporting the rollers 61, a motor 63 mounted on the main frame 62, an oscillator 64 mounted on the main frame 62, and a handle 65.
Starting up the motor 63, the oscillator 64 driven by the motor 63 generates oscillation, which is transferred to the rollers 61 through the main frame 62. Bringing the finisher 60 onto blocks laid in a park or on a footway, an operator grips the handle 65 with the motor 63 being in operation to thereby move the finisher 60 forwardly or backwardly, with the result that surfaces of the blocks are almost leveled by virtue of the oscillation of the rollers 61.
The oscillation rollers suggested in Japanese Patent Application Publication No. 2005-307475 are suitable for further curing a road which is already hard. However, if the oscillation rollers move on a floor composed of half-dry concrete, the oscillation rollers would depress the concrete floor, and rapidly sink into the concrete. Thus, it is not possible to use the oscillation rollers to half-dry concrete. Specifically, the suggested oscillation rollers can be used on a hard road, but cannot be used on a place in which an operator's footprints may remain, such as a floor composed of half-dry concrete.
The finisher 60 of Mikasa Industry Inc. illustrated in FIG. 6 is designed to provide oscillation to blocks laid in a construction site during moving to thereby flatten surfaces of the blocks. Accordingly, the finisher 60 is suitable to flattening hard blocks, because they are not deformed by pressure and/or oscillation transferred thereto through the rollers 61. However, if the finisher 60 is brought onto a floor composed of half-dry concrete, the finisher 60 sinks into half-dry concrete in a short period of time, and hence, cannot work any more, similarly to the above-mentioned oscillation roller.